Leviticus 12:7

והקריבו AND HE SHALL OFFER IT — Two offerings have been mentioned, a lamb and a bird, but it states here ,,and he shall offer it and so make an atonement for her” — this teaches you that only the omission to sacrifice a particular one of these two precludes her from eating the sacrificial food. And which is this? It is the sin-offering, because it is stated immediately afterwards: “he shall make expiation for her and she shall be clean” — that which is intended as expiation (i. e. the sin-offering), upon it does the purification depend (Sifra, Tazria Parashat Yoledet, Chapter 3 4). וטהרה AND SHE SHALL BE CLEAN — it follows, therefore, that until now (until she has brought the atonement offering) she is termed ‘‘unclean” (i.e. she is regarded as טמאה) although she is actually טהרה.

וְהִקְרִיב֞וֹ לִפְנֵ֤י יְהֹוָה֙ וְכִפֶּ֣ר עָלֶ֔יהָ וְטָהֲרָ֖הֿ מִמְּקֹ֣ר דָּמֶ֑יהָ זֹ֤את תּוֹרַת֙ הַיֹּלֶ֔דֶת לַזָּכָ֖ר א֥וֹ לַנְּקֵבָֽה׃

who shall offer it before the Lord, and make atonement for her; and she shall be cleansed from the issue of her blood. This is the Tora for her that has born a male or a female.